1. Technical Field
The present invention relates to a method for manufacturing a liquid flow passage unit, a liquid flow passage unit, a liquid ejecting head unit, and a liquid ejecting apparatus, and is particularly useful when applied to a liquid ejecting head having a liquid flow passage unit for supplying liquid stored in a liquid supply source to a head main body.
2. Related Art
An ink jet recording head that discharges ink droplets from nozzle orifices using pressure generated by displacement of piezoelectric elements is known as a typical example of a liquid ejecting head. In a known ink jet recording head, ink is supplied from a liquid supply source, such as an ink cartridge, filled with ink to a head main body, and the head main body discharges the supplied ink from nozzles by driving pressure generators such as piezoelectric elements or heater elements. For example, by inserting an ink supply needle into an ink cartridge, ink in the ink cartridge is introduced through the inlet of the ink supply needle into the pressure chambers of the head main body.
In some ink jet recording heads, a liquid flow passage unit is provided in a flow passage that supplies ink from a liquid supply source, such as an ink cartridge, to the head main body, and the liquid flow passage unit forms an ink jet recording head unit together with the head main body. This type of liquid flow passage unit fulfills a damper function, that is to say, it controls pressure fluctuation, such as pulsation, of liquid caused by inertial force acting on liquid, for example, when the ink jet recording head unit moves together with a carriage. For this purpose, the liquid flow passage unit has such a structure that an opening of a flow passage for liquid formed in the main body member is covered with a film member so as to form a pressure chamber in a part of the flow passage, and when liquid in the pressure chamber pulsates, the film member bends so as to absorb the pulsation.
JP-A-3606282 discloses a liquid flow passage unit having such a damper function.
When manufacturing such a liquid flow passage unit, the film member is generally heat welded to the main body member. For this purpose, the main body member is made of a polypropylene material (PP material) capable of being heat welded. However, polypropylene materials have problems to be solved with quality. For example, polypropylene materials are inferior to widely-used normal resins in dimensional accuracy and strength. In addition, many burrs remain after molding. Further, polypropylene materials are difficult to bond.
The above-described ink jet recording head is required to be more compact. Accordingly, the liquid flow passage unit is also required to be more compact and more accurate. The liquid flow passage unit is required to have a stable damper function for a long period of time. For this purpose, it is important to stably fix the film member to the main body member while applying an appropriate tension to the film member.
These problems exist not only in ink jet recording head units but also in liquid ejecting head units that eject a liquid other than ink.